Catheter systems are becoming an increasingly common way of diagnosing and treating abnormal heart conditions, in particular, heart arrhythmias. Such arrhythmias can be treated with drugs or by use of electronic devices such as pacemakers. However, neither of these treatments cures the problem but only alleviates it.
In contrast, the use of ablative techniques has been shown to cure arrhythmias. Thus, catheters having mapping electrodes and/or ablative electrodes are inserted through the vascular system of a patient's body so that a distal end of the catheter can be placed accurately in the relevant chamber of the heart. For the treatment of atrial fibrillation, the distal end is placed at or around the ostium of one or more of the pulmonary veins, in turn, to effect ablation.
In still other applications for ablative catheters, the catheter may need to be placed against a wall of a blood vessel or organ, for example, in heating tumors for treatment of such tumors. It is therefore desirable that a distal end of the catheter be substantially planar so that the distal end of the catheter assembly can be placed in contact with the wall of the vessel or organ.